Raise drilling bit

ABSTRACT

A rotary drill bit for producing a raise bore about a pilot hole including a drill head having an upper surface for mounting cutter assemblies. A lower surface spaced from said upper surface and having a drive stem attached thereto. The drive stem being adapted for limited or floating movement with respect to said upper mounting surface.

United States Patent 1 Stanley 1 1 Feb. 18,1975

1 1 RAISE DRILLING BIT [75] Inventor: John M. Stanley, Houston, Tex.

[73] Assignee: Reed Tool Company, Houston, Tex. [22] Filed: Nov. 16,1973 i [21] Appl. No.: 416,362

Henderson 175/73 Pessier 175/53 Primary Examiner-Frank L. AbbottAssistant ExaminerRichard E. Favreau Attorney, Agent, or FirmC. Kucera57 ABSTRACT 10 Claims, 5 Drawing Figures [52] US. Cl. 175/53, 175/61[51] Int. Cl. E2lc 23/00 [58] Field of Search 175/53, 61, 74, 263

[56] References Cited UNITED STATES PATENTS 2,938,710 4/1960 Tannehill175/263 3,231,029 l/l966 Winberg 175/53 3,299,970 l/l967 Anderson 175/53X PATENTED FEB 1 8 1 5 SHEET 10F 2 1 RAISE DRILLING BIT BACKGROUND Thepresent invention relates to earth boring rotary drill bits, andparticularly to drill bits for the drilling of raises extending frommine galleries or shafts at one level to galleries or shafts at otherlevels. Raise drilling comprises the drilling of a relatively smalldiameter pilot hole followed by enlargement of the hole to apredetermined raise diameter by rotating and raising the drill along thepilot hole to form a raise bore between a lower level and an upperlevel, the drill being rotated from above by a drill stem and guided bythe pilot hole. The cuttings produced during such drilling operation areallowed to fall to the lower level.

Raise bores are usually 36 inches in diameter or more and the pilot holemay have a diameter of 9 to l5 inches. Such drill may weigh 5,000 poundsor more. As the raise drilling operation is commenced by rotation of thedrill stern by a drilling rig, the bit may be rotated approximately l to40 R.P.M. while the rig exerts an upward pull on the bit ofapproximately 150,000 to 950,000 pounds. As drilling progresses,sections of the drill stem, which may comprise cylindrical or tubularmembers approximately feet long, are progressively uncoupled at theupper level and the raise is completed by rotating and lifting the drillstem and the raise drill.

It will be appreciated that such drill bits, drill stems and the driveconnections to the drill bits are subjected to severe wear and stresseswhereby the cutters may have to be replaced, and at times the driveconnection to the drill bit may fail, usually in fatigue. Thus it isdesirable that the components may be readily replaceable for relativeease in handling in close places where otherwise the entire bit may bedifficult to maneuver or transport.

SUMMARY The present invention provides a new and improved raise drillbit wherein the components may be readily replaced.

An object of the invention is to provide a new and improved drive stemarrangement for a raise drill.

Another object is to provide a drive stem attachment for a raise drillwhich is adapted to minimize stress ris ers to alleviate fatiguefailures of the drive stem.

Another object is to provide a new and improved raise drill which iseconomical to manufacture and efficient in operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the raisedrill.

FIG. 2 is a view taken along line 2 2 in FIG. 1.

FIG. 3 is a view similar to FIG. 2 but with the drive stem removed.

FIG. 4 is a plan view of the drive stem driving means.

FIG. 5 is a view taken along line 5 5 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings, theraise drill includes an upper mounting member 11 and a lower attachmentmember 12. Circular plates 13 and 14 and outer plate 15 may be securedas by welding to members 11 and 12 to form a drill head 16. Rollercutter assemblies 17 and 18 may be secured to mounting member 11 bywelding or in any other suitable manner. The roller cutter assembliesmay be of a type which is well known in the industry and may comprise astyle of roller cutter assembly similar to that shown in US Pat. No.3,385,385, issued May 28, 1968 to C. M. Kucera, et al.

Referring to FIGS. 2 and 5, a drive stem 20 is shown having a threadedconnection 21 adapted to be attached to the lower end of a drill stem(not shown). The drive stem 20 may have upper and lower flanges 22 and23 secured thereto by welding or otherwise. Support 24 may be secured tothe flange 22 and driver stem 20 and gussets 25 may be secured betweensupport 24 and driver stem 20 to reinforce the connection between thedriver stem 20 and the flange 22. The flange 22 may have driving pins 26adapted to fit into openings 27 in the lower attachment member 12 toprovide means for rotatably driving the drill head 16 with the driverstem 20. Cap screws 28 secure the flange 22 to member 12 of the drillhead 16.

Referring to FIG. 3, the members 11 and 12 have openings 30 and 31therethrough to accommodate the driver stem 20, support 24 and gussets25. The opening 30 is such that there is a clearance between the driverstem 20 and the upper mounting member 11 to provide limited or floatingmovement of the driver stem 20 with respect to the upper mounting member11. This arrangement provides some flexibility of the stem 20 withrespect to the drill head 16 and reduces stress concentrations in thedriver stem 20 in the vicinity of the upper member 11 on which thecutter assemblies 17 and 18 are mounted.

The design of the present invention does not require mating taperedsurfaces or exacting tolerances between the drive stem 20 and the drillhead 16, yet provides a rugged drill bit which is easily assembled ordisassembled by means of the cap screws 28, when replacement parts arerequired.

The provision of a raise drill bit having an upper surface for themounting of roller cutter assemblies thereon, and having a lowersurface, spaced from said upper surface, to accommodate a drivingconnection to the driver stem whereby the driver stem may float relativeto the upper mounting surface, which has severe and irregular stressesimposed upon such surface by the cutter assemblies, results in adrilling bit which is less susceptible to fatigue failures, especiallyof the driver stern, during drilling operations.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape and materials as well as in the details of the illustratedconstruction, may be made within the scope of the appended claimswithout departing from the spirit of the invention.

What is claimed is:

1. A rotary drill bit for producing a raise bore by disintegrating theearth formation surrounding a pilot hole comprising:

a drillhead having an upper mounting member and an attachment portion,

a plurality of cutters secured to said upper mounting member,

a drive stem,

said drive stern being fastened to said attachment portion and extendingthrough said upper mounting member without force transmitting contacttherewith thereby to be floating with respect to said upper mountingmember.

2. A drill bit according to claim 1 wherein the upper mounting member isspaced from said attachment portion.

3. A drill bit according to claim 1 wherein the cutters are arranged todrill the raise bore in a single stage about the pilot hole.

4. A drill bit according to claim 1 wherein the cutters include rollingcutters.

5. In a rotary drill bit for producing raise bores by enlarging a pilothole,

a drill head having an upper portion adapted to have secured thereon aplurality of cutters, and an attachment means,

a drive stem,

said drive stem being fastened to said attachment portion and extendingthrough said upper mounting member without force transmitting contacttherewith, thereby to be floating with respect to said upper portion.

6. A drill head according to claim 5 wherein said drive stem attachmentmeans is spaced from said upper portion.

7. A drill head according to claim 5 wherein the cutters include rollingcutters.

8. A drill head according to claim 5 wherein the drive stem isremovably-fast'ened to said attachment means.

9. A rotary drill bit for producing a raise bore by disintegrating theearth formation surrounding a pilot hole comprising:

a drill head having an upper mounting member and an attachment portion,a plurality of cutters secured to said upper mounting member, a drivestem, said drive stern being fastened to said attachment portion andextending with clearance through said upper mounting member for limitedfloating move ment with respect to said upper mounting member. 10. In arotary drill bit for producing raise bores by enlarging a pilot hole,

a drill head having an upper portion adapted to have secured thereon aplurality of cutters, and an attachment means, a drive stem, said drivestem being fastened to said attachment means and extending withclearance through said upper portion for limited floating movement withrespect to said upper portion.

1. A rotary drill bit for producing a raise bore by disintegrating theearth formation surrounding a pilot hole comprising: a drill head havingan upper mounting member and an attachment portion, a plurality ofcutters secured to said upper mounting member, a drive stem, said drivestem being fastened to said attachment portion and extending throughsaid upper mounting member without force transmitting contact therewiththereby to be floating with respect to said upper mounting member.
 2. Adrill bit according to claim 1 wherein the upper mounting member isspaced from said attachment portion.
 3. A drill bit according to claim 1wherein the cutters are arranged to drill the raise bore in a singlestage about the pilot hole.
 4. A drill bit according to claim 1 whereinthe cutters include rolling cutters.
 5. In a rotary drill bit forproducing raise bores by enlarging a pilot hole, a drill head having anupper portion adapted to have secured thereon a plurality of cutters,and an attachment means, a drive stem, said drive stem being fastened tosaid attachment portion and extending through said upper mounting memberwithout force transmitting contact therewith, thereby to be floatingwith respect to said upper portion.
 6. A drill head according to claim 5wherein said drive stem attachment means is spaced from said upperportion.
 7. A drill head according to claim 5 wherein the cuttersinclude rolling cutters.
 8. A drill head according to claim 5 whereinthe drive stem is removably fastened to said attachment means.
 9. Arotary drill bit for producing a raise bore by disintegrating the earthformation surrounding a pilot hole comprising: a drill head having anupper mounting member and an attachment portion, a plurality of cutterssecured to said upper mounting member, a drive stem, said drive stembeing fastened to said attachment portion and extending with clearancethrough said upper mounting member for limited floating movement withrespect to said upper mounting member.
 10. In a rotary drill bit forproducing raise bores by enlarging a pilot hole, a drill head having anupper portion adapted to have secured thereon a plurality of cutters,and an attachment means, a drive stem, said drive stem being fastened tosaid attachment means and extending with clearance through said upperportion for limited floating movement with respect to said upperportion.